Lubricating process using nonspreading lubricants



United States Patent 3,133,021 LUBRICATING PROCESS USING NON- SPREADING LUBRICANTS Henry Gisser, Philadelphia, Joseph Messina, Havertown, and Seymour Portnoy, Philadelphia, Pa., assignors to the United States of America as represented by the Secretary of the Army No Drawing. Filed Oct. 30, 1958, Ser. No. 770,891 7 Claims. (Cl. 252-34.7) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to non-spreading lubricants which find particular use where a continual supply of lubricating substance cannot be provided; and, where the lubricant film is placed between components having low relative speeds, such that the resistance of the lubricant to spreading and its stability to change in viscosity with change in environmental conditions governs the accuracy of fine instruments such as watches, clocks, fuze mechanisms, etc.

Non-spreading oils are available which show a high degree of performance judged by the ultimate ability of a time piece or meter to perform consistently (that is, to have the same variation in performanceas with a watch, to be slow or fast at a consistent value after repeated checks over long periods of time). However, a

given lubricant may function well under one set of conditions, but be entirely unsatisfactory under other conditions (different time piece, temperature, etc.) The nonspreading component is a main factor contributing to the performance of the lubricant. Therefore, control of the non-spreading ingredient will usually lead to the control of the compounded lubricant.

.A satisfactory lubricant developed for one set of conditions, usually performs Well only under those conditions, and not many others. Then, another lubricant must be developed for the new conditions. The difficulty with the prior art has been that once a lubricant was developed for use under certain conditions, it did not function as well under changed conditions, and a new compound had to be developed or reduced performance accepted. The difficulty inherent in compounding a new lubricant usually resulted in an acceptance of reduced performance.

It is therefore, an object of this invention to present a new series of non-spreading lubricants which may be composed by varying the non-spreading ingredient, thereby resulting in compounds having a wide variety of volatilities, viscosities, etc., which not only may fill many sets of operating conditions, but may easily be compounded.

More particularly, this invention presents a new chemical structure for the non-spreading component of a nonspreading lubricant, whereby a variety of such non-spreading ingredients may be easily composed, thereby resulting in a wide variety of non-spreading lubricants.

The non-spreading ingredient is a diester made from an aromatic alcohol and a dibasic acid, having the general formula 3,133,021 Patented May 12, 1964 where X and R are aliphatic (straight or branch chain) groups with X having up to four carbon atoms and R having up to five carbon atoms; M is 5 through 7, and R is in either the meta or para position of the aromatic ring.

We have discovered unusually good results where the sum of the carbon atoms in the X and R aliphatic'groups does not exceed 4.

Some of the non-spreading components tested and the resulting spreadingdata, when tested at room temperature are included in Fig. A. Spreading of an oil'was determined in the following manner: one inch diameter disks of WD 52-100 steel hardened to Rockwell C-62 were polished with 0, 2/0, 3/0, and 4/0 emery paper and washed under warm tap water while being scrubbed with cotton gauze, then washed successively with distilled water and redistilled methanol. The disks were then dried by clean dry air. A drop of redistilled methanol was placed on the surface of each disk. Complete and uniform evaporation indicated surfaces acceptable for these tests. A drop of oil, 1 to 2 mm. in diameter, was placed on each disk by means of a platinum wire. The degree of spreading was obtained by measuring the change in diameter after '7 and 30 days, respectively; using a traveling microscope.

FIGURE A [Room temperature] Compound 7 days azelate azelate.

The non-spreading component may bepr'epar'ed as follows, using bis(isopropylbenzyl) azelate as an example.

Example I Preparation of bis(isopropylben'zyl)v azelate 0.3 mole p-isopropylbenzyl) alcohol, 0.13 mole azelaio acid, cc. of toluene and 0.5 gram of p-toluene sulfonic acid monohydrate were placed into a 500cc. three-necked flask, fitted with a' stirrer, water trap and reflux condenser.

The mixture was refluxed for four hours during which time 4.7 cc. H 0 were collected. Toluene and excess alcohol were removed by distillation under vacuum with a water aspirator and an oil pump at successively lower pressures. The reaction mixture was neutralized with 2 grams of anhydrous K CO and filtered. The crude bis(p-isopropylbenzyl) azelate is-then twice distilled in a short path molecular still at 20 microns. The middle 60% cut is taken as the product.

To obtain good low temperature characteristics, i.e.,

for functioning at about minus 40 F., the non-spreading such as p-tertbutyl catechol or phenyl-l-naphthylamine is Percent Spreading Aft 30 days OOOO OWH 3 added to the compound. To increase oiliness" of the blend, an oiliness member, such as dodecyl piperidine stearate is added.

Examples of blends which are non-spreading, stable against oxidative attack, and have low pour points (50 to -60 F.) are given in FIG. B.

FIGURE B [Room temperature] Percent by Blend A: Weight Bis(p-isopropylbenzyl) azelate 59.95 Diethylene glycol dicaproate 39.45 Dodecyl piperidine stearate 0.40 p-Tert butyl catechol 0.20 Blend B:

Bis(p-isopropylbenzyl) azelate 50.00 Diethylene glycol bis(3,5,5-trimethylhexanoate) 49.30 Phenyl-l-naphthylamine 0.30 Dodecyl piperidine stearate 0.40 Blend C:

Bis(2-phenylpropyl) azelate 59.85 Diethylene glycol bis(3,5,5-trimethylhexano ate) 39.45 Dodecyl piperidine stearate 0.40 Phenyl-l-naphthylamine 0.30 Blend D:

Bis(2-phenylpropyl) pimelate 59.85 Diethylene glycol bis (3,5,5-trimethylhexanoate) 39.45 p-Tert butyl catechol 0.30 Dodecyl piperidine stearate 0.40

No spreading occurred with these blends after 30 days.

Oxidation stability was determined by means of a dynamic oxidation test using 25 gram samples of oil 'as described in Industrial Engineering Chemistry, vol. 48, p. 2001 (1956), in an article by Gisser, Messina, and Snead. The results on the above blends are shown in FIG. C.

FIGURE C [Oxidation stability oi blends] A B C D.

Oxidation Characteristics: I

Changeinneutralization +0. 041.. +0.07 +0.07 +0.06.

number. Volatile acids formed 0.03-.." 0.03- 0.01- 0.03.

(mg. KOH/gm. oil). I Change in viscosity at +0.14- +0.03. +0.31 +0.18

Change in weight of -1.1 0.8 1.0 2.6. copper strip (mg.). Conditionolcopperstrip, Stained. Stained. Stained. Stained Change in wt. of steel 0.1 1 1--.. 0.1.

strip (mg).

Condition of steel str1p Clean Olean Clean Clean Color of oil before oxida- Light Amber Amber Amber tion. Amber Color of oil after oxida- Dark Dark ark Very tion. Amber Amber Amber Dark p 7 Amber Amount of sediment None None... None None.

formed. a I

We claim:

1. A process for lubricating a fine instrument comprising lubricating said instrument for a lubricant consisting essentially of about 3945-493 parts by Weight diethylene glycol bis(3,5,5-triinethyl hexanoate), about 0.40 part by weight dodecyl piperidine stearate, about 0.30 part by weight of an oxidation inhibitor selected from the class consisting of p-tert-butyl catechol and phenyl-lnaphthylamine, and about 5059.85 parts by weight of a diester having the general formula where X is an aliphatic group containing 1 to 4 carbon atoms, R being a member of the group consisting of hydrogen substituent and an aliphatic group of 1 to 5 carbon atoms attached to the aromatic ring at a position selected from the class of positions consisting of para and meta, and M is a number selected from the group consisting of 5, 6 and 7,.said diester having a pour point not higher than -50 F.

2. The process of claim 1 further characterized by said diester having a sum of carbon atoms within its X and R groups not exceeding 4.

3. The process of claim 1 wherein said diester is bis(2- phenylpropyl) pirnelate.

4. The process of claim 1 wherein said diester is bis(pisopropylbenzyl) suberate.

5. The process of claim 1 wherein said diester is bis(pisopropylbenzyl) azelate. I

. 6. The process of claim 1 wherein said compound is bis(m-methylbenzyl) azelate.

7. The process of claim 1 wherein said compound is bis(2-pheny1propyl) azelate.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES I. and E. Chem," vol. 45, No. 8, August 1953, pp. 1770 and 1771. 

1. A PROCESS FOR LUBRICATING A FINE INSTRUMENT COMPRISING LUBRICATING SAID INSTRUMENT FOR LUBRICANT CONSISTING ESSENTIALLY OF ABOUT 39.45-49.3 PARTS BY WIEGHT DIETHYLENE GLYCOL BIS(3,5,5-TRIMETHYL HEXANOATE), ABOUT 0.40 PART BY WEIGH DODECYL PIPERIDINE STEARATE, ABOUT 0.30 PART BY WEIGHT OF AN OXIDATION INHIBITOR SELECTED FROM THE CLASS CONSISTING OF P-TERT-BUTYL CATECHOL AND PHENYL-LNAPHTHYLAMINE, AND ABOUT 50-59.85 PARTS BY WEIGHT OF A DIESTER HAVING THE GENERAL FORMULA 